SEISMIC MICROZONATION OF AN URBAN AREA IN GIS ENVIRONMENT

Abstract

It is estimated that almost 50% population of the world is living in urban areas. A large number of people are coming to the cities in search of jobs and livelihood. Sometimes they live in those houses and areas that are not safe. Low lying areas which earlier were considered unsuitable for human habitation are being occupied in a planned or unplanned manner. Generally, microzonation of a region is defined as to subdivide it into smaller sub-regions or micro-zones according to a certain criterion to facilitate the implementation. The purpose of this division is to get an area for which various characteristics may be considered fairly uniform. Seismic microzonation may be defined as the assessment of variations in earthquake hazards resulting from differing foundation conditions within a larger area that is prone to seismic activity. In the present study GIS is used for developing a seismic microzonation map for the delhi region. The data used includes different layers which include slope, aspect, ground water table, lithology, physiology, previous earth quake data, faults drainage and geology of the region . For the present study in spatial analyst environment of ARC GIS 8.3, weight analysis is carried out. In this method weightages are assigned to different layers anda commulative weightage map is developed which forms the microzonation map.The weightages are changed for different layers and checking is done with atual environment and previous works to obtain the most suitable seismic microzonation map for Delhi.